Turbine driven compressor



Sept. 23, 1952 B. LJUNGSTROM TURBINE DRIVEN COMPRESSOR 7 Sheets-Sheet 1 Filed Sept. 22, 1945 7 Sheets-Sheet 2 B. LJUNGSTROM TURBINE DRIVEN COMPRESSOR Sept. 23, 1952 Filed Sept. 22, 1945 "It!!! IIiiIIIA Illl'lllll rlli it: In .III I VII! I'll!!! I. l liiilllliililllililll 7 Sheets-Sheet 3 aye B LJUNGSTROM TURBINE DRIVEN COMPRESSOR mwa Fig. 7

Se t. '23, 1952 Flled Sept 22 1945 Fly 2A Sept. 23, 1952 B. LJUNGSTROM TURBINE DRIVEN COMPRESSOR 7 Sheets-Sheet 5 Filed Sept. 22, 1945 B. LJUNGSTROM TURBINE DRIVEN COMPRESSOR Sept. 23, 1952 7 Sheets-Sheet 6 Filed Sept. 22, 1945 Illllllll' 'lllllllll Fig. /3

III

WIT] IIIIIHHH Sept. 23, 1952 B. LJUNGSTRGM TURBINE DRIVEN COMPRESSOR 7 Sheets-Sheet 7 Filed Sept. 22, 1945 Patented Sept. 23, 1952 TURBINE-DRIVEN COMPRESSOR v Birger Ljungstriim, Stockholm, Sweden Application September 22 In Sweden Sept 1945, Serial No. 618,042 ember 23, 1944 1 Claim, (Cl. 230 116) The present invention comprising a gas turbine and a compressor directly connected thereto and in which the power is delivered from the gas turbine-through combustion gases of high velocity and/or high pressure. Saidcombustion gases may be utilized either for the propelling of aeroplanes, projectiles, ships or carriages according-to the reaction principle or for driving another gas turbine in which the dynamically available energy of the combustion gases as delivered from said first-mentioned turbine .is utilized for, driving a power shaft or shafts.

Said last-mentioned turbine, hereinafter re ferred to as the power turbine, especially when it is desired to obtain a compact plant, may be arranged as a direct continuation of the driving turbine of the compressor, or it may comprise a separate machine, the gas inlet of which communicates with the combustion gas outlet of the first turbine.-' In such case; for instance, the power turbine 'may be situated coaxially outside the'fir'st turbine in the outlet of an additional combustion chamber located between the two turbines; In the said lastmentioned case-the rotary "machines 'with -'as-- sociated combustion chambers may be assembled so as to form a ci-rculation system. in order-to permit an efficient utilization of,.the'energy and heat content of the driving fluid. In such a circulation system the coaxialpositioning of the turbines with relation to each other may be dispensed withand a, heat'exchanger may be inserted in the system where required: A

The combined compressor and drivingturbine therefor comprises three main parts, comprising two rotary engines or machines, namely a gas turbine and a turbine type of compressor, both of multi-stage type, and a shaft system provided therebetween, which comprises. a set of tubular shafts concentrically surrounding each other and rotatable independently of each other, and in whichi'ach tubularlshaft is connected at one end to blade wheeljlior wheels) of the turbine and at the other end (or wheels) of the compressor. V v w The above said shaft system DQrmits-tr'ans:

to a blade wheel mission of power from individual blade wheels of the turbine to individual blade wheels oi, the compressor. 'Merely by adjusting the anglesf blade it is'possible to secure'an'y desired-pe ripheral speed of the individual "lblade' wheels, as for instance, the same speed, irrespective of differences indiameter, and cause them-to runin the samedirection or inopposite-directions.

If, by testing, apreferred type-pf blade' whee'l relates a power plant is obtained, then the proportions of this blade wheel may be applied to all sizes of wheel of one and the same engine or machine, provided the dimensions of the various wheels are selected in proper progression and all of them rotate'at the same peripheral speed. The centrifugal force, the efiiciency, the maximum output of, power, and the speed of flow of the driving fluid may in such case be made substantially equal for all blade wheels, irrespective of such changes of pressure and/or volume as may occur-during sumptionand increasesT the radius of action.-

the flow of the driving fluid due to the operating conditions. 4 In case of a'single rotating system theinvention allows the connection of any or all of the tubular shafts-at one end or both'to more than one blade wheel, say two or three, or to different numbers of blade wheels at opposite ends. Sucha modification reduces the number of tubular shafts required for a givennumber of blade wheels, but, on the other hand, reduces the possibility of obtaining a maximum "output from each blade ring, and causes a corresponding increase of theweight ofthe rotary system, The most eificient way in which to use the invention is to connect the tubular shafts to but a single blade wheel at either end. In this case every second blade wheel of the turbine and the compressor rotates in one direction and the remaining blade wheels in the opposite direction so that adjacent blade wheels of one and thesame engine or machine always rotate inopposite directions. Of course, the angles of blade. are selected so as to allowthe driving fluid to pass from'one blade wheel to another without the aid of guide blades inserted thereshaft, and to correspondingly reduce; the. damn-' sions of the plant as a whole; The reduction of the weightreduces, especially in 'cas'e of an ae'roplanewthe power andl-fuel com.

Invested in a larger plant the reduction of the weight may be utilized either to obtain a higher speed or a higher efficiency.

In the accompanying drawings,

Fig. 1 illustrates the invention as embodied in a machine for driving an aeroplane according to the reaction principle. Fig. 1 shows a diagrammatic axial section of the machine.

Fig. 2 is a side elevation, partly in axial section, of one end of the shaft system of said machine.

Figs. 2A and 2B are detail views of means for locking and sealing blade wheels on shafts.

Figs. 3-6 are detail sectional views showing the attachment of the blades to the blade wheels.

Fig. 7 is a section of the attachment of a blade on a larger scale.

Fig. 8 shows a form of blade roots.

Fig. 9 is a diagrammatic side view of the .power plant as inserted in the wing of an aeroplane.

Fig. 10 is a front view of said wing and plant.

Fig. i1- isa side elevationpf atubularshait system.

Figs.12 and 13 are diagrammaticviews ofpower plants, the turbine and compressor of which are providedwith cylindricalcasings. I

Fig. 14 is a-diagrannnat-icpart; sectional side elevation of; an; embodiment; of the invention including besides the compressor and associated driving turbine a powerturbine.

Fig. 15 is adiagrammaticview-of the invention as embodied in a circulation system.

' In Fig. 1 the powerplant is shown as located at the, rear end of an aeroplane, the-arrangement being such as to allow a'readydismantling of the power plant. The power plant illustrated in this figure includes in- ,addition to the three main; parts above. stated a, combusticn chamber located between the turbine and the compressor and another. chamber provided 'inth'e outlet of the turbine which is adapted'for effecting a 'recombustion, for instancetoallow agforced operation. Since the combustion means do not form part of this invention, they are not shown inthe drawingzthey may beassumed to-be of well-known design. 7

The power plant shown has no power shaft; the delivery of power being effected exclusively by reactionin the turbine outlet.

Themounting of shafts and turbine discs requires both special bearing arrangements and special means for cooling and; axially balancing the bearings and the turbine discs as well as special'forms of the turbine and compressor casings and special means for tightlysealing the ends of the blades, as will be hereinbelowset forth.

It is preferred to use an oil mist lubricating system particularly-in caseof a shaft system mounted in ball bearing. :Inthis-connection-an auxiliaryhigh pressure fan blower-is provided which-takes its air from :the. combustion chamber located immediately behind the compressor through separate pipesrthefiattenedsections of which-9 :05am: inle o theicompressor in order to form ,a .cooling; device; for the: air withdrawn which; is :thenpas d-thr u h an oil m st .1 1- bricating device or devices :placed in front; of tbeinl t of the iarrblowe I v The said auxiliary; fan; blower 3' may 2 be idrivcn by. mean f toothed-eearinesfrom the first blade wheel of the compressor or in any; other; appropriate way. j

To start the plant I useras'tartin rmotor', preferably petrol :driven, provided with; an electric starting mechanism. Inserted between said 4 starting motor and the fan blower is a pawl and ratchet gear.

The first and the last blade wheels of the coinpressor and the turbine together with the respective tubular shaft are thus started by the action of the starting motor via the fan blower and the associated toothed gearing, thereby forcingthe-air. or driving fluid of the plant in axial direction through the acon' 'pressor, the combustion chamber and the turbine. The combustion .process in the combustion chamber being simul- I taneously started, the plant as a whole is thus -sta-rted.- -Thestarting motor and its pawl and ratchet. gear man then be stopped.

According to an embodiment of the invention therpower: plant comprises a number, say four, similar-nnits, placed in the wings of an aero- .plane,

,This method of mounting the plant has for its object to reduce the air resistance. As seen from the illustration of this embodiment, the axial "distance fbetween the compressor and the turbinewill'be comparatively long, causing a corresponding lengthening of v the intermediate tulouiarfv shaft-system.

CSince the --highspeeds occurring in a plant of this character due to its comparatively small diameterwould'jcause the'long tubular shafts to exceed" their critical: speed, it they were made altogether cylindrical," the said shafts are formed with conically'tapering ends, the thickness of wall required. at the ends being, correspondingly reduced towards" the middle of the'shafts. resulting in an increased criticalspeed. A- tubular. shaft system of this construction prevents the-assembling of the tubular shafts by pushing theminto. eachother'. in finished state. To. overcome .thisf. .di'ificulty the various tubular shafts mayeithenbe madein two parts connected together. by weldingor otherwise in assembling. thesystem, ,or the shafts may first be cylindricalto allow their insertion into each other and then conformedat their ends to the cross section: desired accordingasthe mounting is proseeding shaftby shaft from inside outwards. The various; steps involved inzthis method of mounti-ngdo; not t-cause .any essential troubles, particularlyas differences inrespectof the radial plays of theshaitsare of no'importanceas far as the operation of theshaft system .is concerned.

The fastening of the'blade wheels to the ends of the tubular shaftsmay be facilitated by thickening the walls of'the shaft ends by an amount corresponding to" the plays existing between entirelycylindrical-shafts; As an alternative, the shaft endsbf-theassembled shaft system may be provided with separate stifiening pieces at their ends irrthe-fornr of bushingsattached by pressing or welding 'whichmay-either be provided with means] for "receiving .the' blade wheels or afterwards workedffor thesamepurpose. I

"The; labyrinth packings hereinafter referred to inithecspecification andjthe claimfmaybe of well known character. and dra'thercfore, not illustrated in detail but,. .only indicated in conventionalmanner. .Theinvention has nothing to dowith theconstructionof such packings but includestheir use in. novel and characteristic combinationswith aview to lubricating the tubular. shaft system, cooling the blade wheel systems-and obtainingaa good sealing-between the blade wheel systemsandathereasings of the compressor and the turbine.

To this' end avfeature or the invention relates 7:51 tova noveliconstruction or the blade wheels proper in which each blade wheel is composed'of two axially abutting discs between which there is a space surrounded by walls the thickness of which decreases outwards like the thickness of an undivided blade wheel of conventional design. Said novel structure of the blade wheels has for its purpose to permit a good cooling of the blade wheels so that their surfaces facing each other may be situated at a short distance apart and provided with labyrinth packings for cooling purposes.

The blade wheel structure above descri ed permits shaping and mounting the labyrinth packings with a view to obtaining both a balancing of the axial thrusts appearing between the blade wheels and a reduction of the quantity of lubricating oil and cooling fluid passing between the wheels of each pair of wheels. Thus it is possible to control the distribution of the cooling fluid to the various pairs of Wheels and to reduce the total quantity thereof required. The dimensions and power of the fan blower and the losses inherent thereto may be reduced accordinglyr Though, hereinbefore, the blade wheels have been assumed as rigidly connected to the tubular shafts against axial movements, it is evident, however, that they may be connected thereto by axially adjustable means, provided the axial position of the blade wheels with relation to each other is stabilized and maintained by the use of appropriate labyrinth packings subjected to axial pressure transmitted by the cooling fluid.

The flow of the cooling fluid from between the outer edges of the blade wheels to the driving fiuid passing between the blade rings serves an additional purpose, inasmuch as the cooling fluid prevents leakage of the driving fluid into between the blade wheels, that is, past the inner ends of the blades.

The leakage past the outer ends of the blades, that is, past the outer periphery of the blade wheels, involves another problem, namely sealing each blade ring with respect to the inside of the turbine and compressor casings. This problem is intimately related to the introduction of the tubular shaft system and the use of double rotation.

The turbine and compressor casings Support no guide blades or the like between the blade wheels. Instead thereof special packing means of heat elastic kind are provided which may suit, independently of the casings, such changes of the radius of the rotary system, including the expansion and contraction of the turbine blades, as are due to sudden changes of load or to a quick starting. By this means a lagging of the expansion or contraction of the turbine and compressor casings resulting from said changes of temperature do not require any increased plays. This means a specialadvantage, since the packings of all'blade wheels are positioned at the greatest radius of the blade wheels where there are very great falls in pressure between each two adjacent blade wheels due to 'the'double rotation. T

The packing means provided on the inside of th turbine and compressor casings comprise well known expansion elements.

Instead of mounting the shaftsystem on a tubular stationary shaft, as above mentioned; I may use-the innermost, or central, rotary tubular shaft to support the surrounding shafts; To this end said innermost shaft should be mounted in bearings at both ends. In this case the power to drive the fan blower may be derived from one free end of said shaft.

As shown in Fig. 1 the power plant is mounted in the rear end of the aeroplane body by means of a flange I. The main parts of the plant comprise the inlet 2, the compressor 3 with associated casing 3b; the turbine 5 with associated casing 5b, a cylindrical wall 4b connecting the casings 3b and 5b which forms a combustion chamber 4, and an outlet 6. Said members form together a unitary structure surrounding the tubular shaft system 1 supported by a central stationary shaft l2 which is guided at both ends by bushings 8 and 9 carried by or formed integrally with stationary guide blade wheels l6 and II provided at opposite ends of the compressor and turbine bladings, respectively. The said 7 central shaft [2 supports ball bearings I3 and I 4 serving to guide the first pair of blade wheels l5, l6 and the associated tubular shaft l'l carrying said wheels.

The tubular shaft system shown in Fig. 1 comprises a set of rotary shafts l824, which may rotate at individual peripheral. speeds with adjacent shafts rotatin in opposite directions. The blade wheels of the turbine connected to the shaft system which are numbered Ilia to 22a, and those of the compressor which are num bered [5b to 2Ib, are all mounted on ball bearings to permit independent rotation of each individual shaft. In the drawing the first and last ball bearings belonging to the compressor are shown at I 3 and 26, respectively, and the first and last ball bearings of the compressor are shown at 25 and 15, respectively. The innermost ball bearings of the compressor and the turbine, namely 26 and 25, are supported by guide blade rings 28 and 21'andthe insulating bushing 29 inserted therebetween, in order that also the outermost tubular shaft 24 may be positively guided by the casing of the plant.

The tubular shaft system together with the blade wheels connected thereto is positively guided at its outer ends by the ball bearings l3 and I4 and in the middle of the system by the ball bearings 25 and 26 as already stated, whereas the ball bearings situated between l4 and 25 and between [3 and 26 are centered within the turbine and compressor casings respectively by the action of said first-mentioned bearings.

The cooling system of the power plant com prises means for withdrawing air from the combustion chamber 4 through pipes 30 symmetrically arranged around the plant, said pipes 36 passing through the air inlet 2 of the power plant in the form of flattened pipes 3| connected at both ends to concentric collecting pipes 32 and 33 for constituting the cooling system of the plant. From said collecting pipe 33 the cooled air is passed through one or more radially positioned pipes 34 to one or more lubricating apparatus 35 operating according to the mist system, and from there the air is passed to the inlet of the auxiliary high pressure fan blower 36. The fan blower forces the oil mist at an increased superpressure through the tubular shaft l2 into the centre of the shaft system along the entire length thereof.

The said high pressure fan blower. is con-- nected by means of toothed gears 31 and 38 to a blade wheel I5 and is further connected by means of the pawl and ratchet gear'39 to v the starting motor which maybe provided with anelectric automatic starting device, not

shown.

JznIFigJ 1' Zthfil reference. numeral 1M indicates the entrance of the cooling' andLlubri'cating.oil mist into theispaces between. the various. tubular shafts, in whichzspacessaid :oil mistcmay be passed to the various rotary elements of the plant.

In Fig. 2 isishown an axial section of one end ofthe shaft system including the stationary central pipe l2 and the rotary shafts i3 andl24. In this drawing both the guiding ball bearings is and 25 and thelother ball bearings which are situated .betweenthe-turbine disc to centre the turbinediscs land the rotaryshafts are shown. The *turbineadiscs 1 8a andLZZa are fastened to the.- respective tubular' shafts i by being screwed on-thevthreaded'ends :thereof. Said threaded ends are of aigreater thickness than the remainder of the shafts. The fastening of the turbine disc; 17a is also: effected by screwing, but in thiswcaseithe turbine dlsc'isnot in direct contact with the shaft end, inasmuch as asset of wedges 42 .of thin-sheet metal is inserted between the shaft iand-the turbine disc, said wedges being flexible, 'so .that Ithey may act as seals'for the locknut lS. The bladeiwheel its illustrates another -modification in which the tubular shaft l8.is .providedwith a bushing 4 pushed thereon which isconnected' to the shaft bywelding, as indicatedatdb. Theconnection between the blade wheel and said bushing is efiected by meansof keysit and lock'nut t? with-associated washer 43.

Figs. 2A. and 2B show details of said tvzolastmentioned fastenings.

.The abovesaid different ..fastening methods may be applied to all blade-wheels. The second method requires mounting .of the hubs of the blade wheels subsequentto the introduction of the tubular shafts intoeach other, which prevents the shafts from being dismantled in the same way.

As indicated at 49 'the cooling fluid may be in troduced-betweenall tubular shafts through a radial set of apertures,.while as shown at as the discharge of the lubricating fluid from between the tubular shafts may take place at axially displaced, points to the spaces between the blade wheels inside the-bearings thereof. As already indicated the cooling and lubricating fluid is then passed through the ball bearings radially outwards between. the blade whee1s,-as will be clear. from an inspection. of Fig. 3.

Said FigFB shows anaxial section of two adjacent blade wheel discs bit-and 5327 with associated shaft end ball bearings. .Radially outside the ball-bearings are labyrinth packings 5i and 52 situated at. radially spaced places adjacent theball .bearingsland the outer periphery of the discs, respectively. he cooling and lubricating fluid willthus flow to the blade system through the labyrinth .packlhgs and escape together with the driving fluid. It is to be. noted, that labyrinth packingsJmay also be provided along the remainingportion of the opposite surfaces of the blade wheels.

AccordingtoFigB the blade'wheels are each composed'of'twoaxiallyi'displaced discs 53 and 53b welded together at their inner and 'outer peripheries so .that they will constitute a hollow body the space of which is'indicated by the reference numeral 55. The purpose of this construction has already :been pointed out hereinbefore. The blades shown in Fig. may be fastened to their "respective "blade wheels by Welding, preferably resistance welding.

:Eigs. 4,15: and ;6 lillustratesanother .method of fastening theblades between the two discs of each blade wheel. According-to this method the blades are. fastened to oriormed integrally "with blade :roots 55- of special shape, as shown in Figs. 6, 7 and 8. Fig. '7. illustratesthe fasteningmethod onallarger: scale. It is evident from the drawing that the caulking wire 56 causes a firm engagement at -51 as and for transmitting the centrifugal stresses and interconnecting the two discs 53 and 53b.

Eigsza and 5 show a .form of blade roots '55 havlnga thin radialweb EBprojecting from its inner surface said :web dueto its small thickness-having aigreatresistance to heat conduction thereby reducingathesamount of heat transmitted from .thebladesand the bladeroots to the blade wheel discs.

Fig. dillustrates .a .formcf tightening device provided on the-inside of. .the turbine .and compressor 'casings, which are adapted to prevent leakageofdriving. fluid beyond the tops of the blades or beyond .theouter-edges of the blade wheels. In its most simple form said device consists of. axialprojections 59 at theinside of the conical casing 512. Asshown attic said axial projections may bereplaced by thin sheet metal rings of angular cross section, which are insorted in grooves formed inthe casing and sealed intoeengagement therewithby means of caulking wires 6!.

Fig.4 illustrates amorestructural form ofv device forwthe same purpose. .Here, said .device comprises a: separate ringti connected by means of anexpansionring .63 to .a' seating ring 64 seatedin agroove-of the casing 5b and sealed in thishengagement by .means of a caulking wire 65. This device allows an. independent contraction of the ring 62 with relation to the casing 522 due to changes of temperature and operation. A vchannel-shaped ring 68 situated inside ringSZ which isprovidedatthe top of .the blade is formed with two tightening ridges which may be worn in operation with but little heat generation .until the play required by the operation is obtained.

In Fig. Qisshown a power plant according to the invention as located in the wing .ofan aeroplane. .Inthis case the-compressor 3 and theturbine'b arerconn'ected for-practical reasons to each other by means of a very long'tubular shaft system 6 1, the construction oflwhich is shown in'Fig; ll. Said shaft system.may be assumed to be constructed according to the principles above set forth.

In Fig..10 the wing with thepowerplant therein is shown infront. elevation, the air inlet. opening being specially indicatedv and the entire structurelbeing. shaped .witha view to obtaining the smallest airresistance possible.

.Figs. -12 .and 13 .are diagrammatic views of power. plants having. cylindrical instead of conical compressor K and-gas turbine T, .the diameters of both being either.equal,.as shown in Fig. 12, or different, asshowniin Fig. 13, withthediameter of the compressor considerably greater than that of the turbine.

.In aeroplanes for "-very high-spee'ds the air resistance will be' considerable evenas far as the individual reaction plants are concerned. The air' resistance ofrsuch a plant is approximately proportional to the largest sectionarea of the plant, Said area "cannot be'reduced beyond the dimensions determined= by the diameter of the ml re'ssor and the inlet area thereof as calculata correspondingreduction of the diameter of the compressor as well as of the air resistance. It

is to be noted that a further reduction of' the diameter with larger angles of blade at the inlet is economically grounded, even at the cost of the efliciency of the compressonii this measurement results in acorresponding reduction of the diameter of the plant, that is to -say, a reduction of air resistance and weight and thus also of the weight of the aeroplane and thetotal air-resistance thereof This fact seems not to have been duly considered in case of priorproposals.

, As a result, I obtain a power plant having a comparatively very small compressor diameter,

- ,while the turbine diameter may be still more reduced without interfering with a high efiiciency. Thus, the plant as a whole will obtain the smallest outer dimensions possible or the smallest outer air resistance. I i

The diameters of the compressor and the turbine will, however, even at the highest eiiiciency, be nearly equal. It is to be noted that the figures of the drawing above discussed show examples of the invention only but do not mean limitations of the scope of the invention.

Hereinbefore, the invention is described as applied to a power plant for the propelling of aeroplanes according to the reaction principle, It is to be noted, however, that the invention may be applied in other connections, where combustion gases, produced under a high pressure, are utilized, as for instance, for the propelling of projectiles, ships, carriages and so on as well as for stationary power generating purposes.

Examples of such modified plants are illustrated in Figs. 14 and 15.

In Fig. 14 the numeral IOI designates a stationary guide blade ring provided at the inlet of the turbine type of compressor, while I02 designates the blade wheels of said compressor. The guide blade ring I M is connected at its outer periphery to the compressor casing I03 and at its inner periphery to a bearing I04 supporting the shaft I05 of the power turbine to be hereinbelow described. The blade wheels I02 of the compressor are of diameters gradually decreasing from the inlet towards the outlet of the compressor. Each blade wheel is supported by a tubular shaft I06 which carries at its other end a corresponding blade wheel I01 of a gas turbine. In the drawing the tubular shafts I06 are not shown to their entire extent in order not to render the illustration obscure but only their ends are shown. The individual tubular shafts I 06 may rotate independently of each other. To this end ball bearings I08 are inserted between the blade wheels I 02 of the compressor, and similar ball bearings I09 are inserted between the blade wheels I01 of the turbine, Between the outlet end of the compressor and the inlet end of the turbine is a stationary partition I I0, which projects outwards into a combustion chamber II I surrounding the compressor and turbine casings. Said partition forms a baflle which acts to guide tda driven shaft.

turbine.

Both the turbine pipeof compressor I02 and the gas eez fil are dq ib rot n t ay Wi out departing from the principle of the invention'be replaced by single rotating-machines. As

an immediate continuation of the gasturbine III! that drives the compressoris provided a single rotation power turbine of conventional type comprising a set of stationary guide blade rings H3 and a corresponding set of rotary blade -wheels H4. The latter are connected to thesaidfirstmentioned shaft I 05 which is mounted at its one end in the bearing I04 above referred to and at its other end in a bearingllipositio'nedoutside the turbine II4, preferably-inconibinatlon with the outlet-thereof. Outside the bearing I I5 the shaft I05. carries a flange II 6 for its coupling The exhaust gases expelled from the turbine H4 are discharged through the outlet II! to be then pas'sed, for instance, to a plant for recovering their heat content.

In the plant diagrammatically illustrated in Fig. 15 the gas turbine adapted todelivr'power through its shaft is mounted separately at a distance from the compressor and its driving turbine. Provided betwee'n'the outlet of the compressor I20 and the inlet of the driving {turbine I2I is a combustion chamber'fI22"and1.in.front of the power turbine I23 is another combustion chamber I24. The system also includes a heat exchanger I25. In order to render the insertion of the heat exchangers into the system more easily the compressor and its driving turbine are so related to each other that their outlets are facing each other.

The fluid to be compressed is drawn into the compressor as indicated by the arrows a and passes from the compressor through the heat exchanger I25 where its already very high temperature (say 300 C.), due to compression, is further increased (say to 450 C.) by the admission of heat from the gases discharged from the power turbine I23. The fluid then enters at this high temperature the combustion chamber I22 where it is mixed with fuel and the mixture resulting is ignited. The combustion gases produced which obtain a still increased temperature (say 900 C.) enter the driving turbine I2I of the compressor where they deliver part of their energy content under reduction of their pressure and temperature (say to 600 C.). The gas expelled from the turbine I2I is not passed directly to the power turbine I23 but is first led through the combustion chamber I24 where fuel is added and combustion again established. This produces another increase of temperature up to the maximum value (say 900 C.), and the heat gases produced enter the power turbine I23 where their energy is transformed into Work delivered through the shaft I26. The gases discharged from the turbine I23 maintain still a comparatively high temperature (say 500 C.) and are therefore passed through the heat exchanger I25 Where part of their heat content is recovered. The remainder of the heat content corresponding, for instance, to a temperature of 350 0., may be utilized for water heating and/or similar purposes.

The temperatures above stated within parentheses are, of course, quite approximative and 11 mentioned Only-as an-illustration ofthe'heat sitnation within'the plant Y I I QEv'eninqease bffihe structures illu's t raped in Figs. '14 and 15 modifications may be made by the use of compressors and driving turbines therefor of cy1'indiica1-- shape instead -ofthe" conical Compressors "and; driving turbines shown. These 'in'odificat i dns inayf also be pensidered to be illustrated by' Eigs.-"l 2**a1id -13, where-K indicates" the turbine type iof compressor and T" the driving turbine flthereforfsaid engines "may either-he Of" 17he{same diaimetergas shownfinfig.

' 12," cir bf "different fiialmetersi-as shown in Fi'g; 13.

let} at itsibther endfia-stationary Shaft centrally arrgingdm said' c mgm eat or tubi'ilar' rptatable shafts; gongentrieally surrounding. "said fcentral 's haffi' with the endlshf each inner tubular shaft projecting beybndthe ends of the adjacent surrounding 'shaftfacompressbr blame"Wheel" supported by' one prgie'cti ng "end of" eabh tubular shaft, a turbine-blade wheel supported; by the other projecting fe'rid; of each tubular "shaft, a bushing stationgily arranged in the easing bladewheels'being axielHyspaced'fi om each other and havingradially spazced eoncenfric: flange s jon their sides facing each jbther so as "to' enclose an *annular space 'between'eaeh two adjacent i 'ph i erfl s ib f ebmbinatidp offa slpqplf' shaped casing having an air inlet atiits one' eng and anjexhahst gas out- 'sizfiifaf simmer spaces-"fbrmed bween the bIzi-de wheels of the innermost tubular she} aaidthe a befiwe'em the aiid smd saefimnary 

